Spontaneous confabulation, reality monitoring, and the limbic system - a review

Patients with anterior limbic damage may present a distinct syndrome, spont aneous confabulation: they fail in common memory tests, act on the basis of previous habits rather than currently relevant memories, produce confabula tions composed of elements of past true events, are disorientated, and are absolutely convinced about the veracity of their perceived reality. Spontan eous confabulation is independent of other false memories, such as, provoke d confabulations or illusory recognition. Studies showed that spontaneous c onfabulators fail to suppress (inactivate) evoked memories that do not pert ain to ongoing reality. Rehabilitation differs from other memory failures. Prognosis depends on the lesion site, but recovery is always associated wit h recovery of this suppression capacity. Lesions typically involve the post erior medial orbitofrontal cortex or its connections in the basal forebrain . Imaging and evoked potential studies in healthy subjects support the idea that the anterior limbic system provides a reality monitoring mechanism wh ich selects memories of current relevance by suppressing (inactivating) cur rently irrelevant memories. This mechanism appears to adjust die cortical r epresentation of activated memories before their content is recognised and consolidated. Comparison with animal studies suggests that human reality mo nitoring is a property of the brain's reward system. (C) 2001 Elsevier Scie nce B.V. All rights reserved.